Coastal upwelling systems are characterized by a high primary productivity, due to wind driven currents that bring to the surface deep, nutrientrich, water. Intense productivity in these regions is frequently, but not systematically, associated with the formation of organic-rich sediments. The highest rates of organic matter (OM) accumulation in the modern ocean are thus found in some areas beneath upwelling (Calvert, 1987) and high TOC values, up to 16%, were observed for upwelling sediments offshore Peru and Oman (e.g. Eglinton et al., 1994; Ltickge et al., 1996). Upwelling regions thus play an important role for OM burial in marine sediments, although they represent less than 1% of the total surface of ocean. Indeed, the comparison of the assumed location of palaeo-upwellings and of organic-rich deposits indicated that up to half of marine source rocks may originate from upwelling zones (Parrish, 1987). Understanding the mechanism(s) of OM preservation in coastal upwellings and the factors that control OM accumulation in such areas is therefore important. Accordingly, a nmnber of molecular studies were carried out on the OM of sediments underlying upwelling systems. However, they have mostly been concerned, so far, with soluble constituents and they mainly dealt with samples originating from the Peru upwelling.